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JOHN MILROY, 0F EDTNBUBGH, GREAT BRITAIN.

Letters Patent No. 64,023, dated April 23, 1867.

IMPROVED EXGAVATO.

TO ALL WHOM IT MAY CONCERN:

Be it known that I, JOHN MILROY, of Edinburgh, in the county of Mid Lothian, Kingdom of Great Britain and Ireland, have invented a new and useful Improvement in Apparatus for Dredging or Excavating; and declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawing, and to the reference numerals and letters marked thereon.

Y My invention relates to improved apparatusfor dredging or excavating in a simple, economical, and expeditious manner, and the apparatus is more particularly designed for making excavations on dry land or under water within cylindrical iron or other casings, such as are frequently used in forming piers, foundations, or pillars for supporting bridges and other structures. 'My improved apparatus may also be used for sinking pits and wells, for dredging, and'for other similar purposes.

And in order that others skilled in the art may properly understand my invention, and the manner in which my improved apparatus is to be used, I will now proceed to particularly describe the same, premising that Figure'l, on the drawing, is a plan of the apparatus; and that Figure 2 is aside elevation thereof, with the right-hand half shown in vertical section.

Inl the improved apparatus a series of spades or digging and lifting blades, 1, is hinged to a horizontal framework, 2, with a raised rim, into the interstices of which framework they exactly fit when closed. The frame 2 may b e circular, square, or polygonal in figure, to suit the shape of the excavation to be made with it, but in the modification represented in the drawing it 'is octagonal in plan. The spades 1 are of a form varying with that of the frame 2; generally they are in the form of a triangle with a piece cut eti' the apex, as represented in the drawing, and they are hinged (in this example) to the rim or outer sides of the frame, whilst they are formed with sides projecting inwards to enable them to take better hold of the earth. .When the apparatus is being lowered over the spot to be excavated the spades l are open, and hang vertically, or nearly so, as shown in fig. 2. The apparatus is lowered as far as it will go with the spades in the open vertical position, and the spades having settled into the earth, or having been forced into it in the'manner hereinafter described, are drawn inwards through the ground and earth with them, each into its own opening iu the frame 2, which is thereby formed into a close vessel, and is drawn up in that condition with a quantity of earth in or upon it. The bottom or narrow ends of the spades 1 are brought up against a ring forming the centre of the frame 2, and Connected by radial ribs to the outer part of the frame. A lining or packing of vulcanized rubber is applied to the centre and tothe radial ribs for the edges of the spades to close upon to form a tight joint. The various changes necessary to 4bring about the above results are effected by the means now about to be described. With the end of the main rope or chain 4, which is worked by an engine or other hoisting machine, and which is employed to raise or lower the apparatus, the excavator, as it may be termed, is attached by two sets of chains A B. The chains of set A, all of equal length, are Veach fixed tc .the frame 2, and after uniting upon a ring are joined to the main chain 4, a short-way above its junction with the other set of chains B, by a length of single chain, 6, which is looped up, when the apparatus is descending, by a monkey-hook, 7, or otherwise. The set of chains A is represented as consisting of four chains; there may, however, be eight chains in this set which may pass over the rim of the frame to points of attachment on the backs or outsides of the spades 1. In this case the spades 1 must be tted with stops to arrest them in the vertical position, as when the chains A are drawn tight they will otherwise turn them too far outwards. There are eight chains of set B, all of equal length, and they are attached at their lower ends each to the inside of a spade, 1, and at their upper ends to the end of the mai-n chain 4. These chains B are for the purpose of pulling in the spades 1 up to the frame 2 with the earth which they drag with them, and for raising the whole machine to the staging above. When lowering the excavator the connecting chain 6, of the outer set of chains A, is looped up by means of the monkey-hook 7, (the chains of set B being thereby rendered quite slack,) until the excavator reaches the bottom. The monkey-hook 7 is then thrown out of gear by means of a rope, S, which slackens the outer set of chains A, and upon the hoisting being set about, the inner set of chains B are brought into tension, draw in the spades 1, and raise the whole machine to the surface. It is frequently necessary'to insure the excavators being kept and forced down at the moment when the spades 1 are being drawn into their places in the frame 2.

This may be eiected by means of two chains which'are fixed to opposite sides of the frame 2, and which pass under pulleys held down Within a convenient distance from the bottom ol' the excavation, and thence up to winding axles at the staging above. The bottoni pulleys for the holdingdown chains may be carried by wooden spars placed inside the cylinders, being kept apart at their lower ends by being there fixed to opposite sides of.

a strong iron hoop, whilst their upper ends are fixed to the cylinder itself. These spars or leaders will incre downwards with the cylinders as the excavation proceeds. The chains are l1ai1led tight as the excavator descends, and when it has reached the ground sutlicient strain is put ou them to force the spades 1 into the earth,.to keep the frame 2 from rising whilst they arc being drawn inwards, and to insure their taking hold of the ground. As soon as the workmen feel that the spades 1 are drawn close in, the holding-down chains are' released, and the excavator is raised up to a height convenient for emptying its contents. A lorry or wagon is moved beneath the excavator for it to rest on; the outer set of chains A is then hooked up, and the exea-f vator being raised alittle the spades l fall open, discharging their contents into the lorry, which is then removed and the excavator is lowered again. In some cases the frame 2 may be conveniently made sulicicntly heavy to keep down of itself, whilst the spades 1 are being drawn in in which cases the holding-down chains may be dispensed with. The proportions and form of the parts of the apparatus and the special appliances used may be varied to suit the character of the spot to be excavated in each ease, whilst the economical applicability of the apparatus will of course depend upon thenature of the soil to be dealt with. Thus, the centre of the frame 2 may be held by inclined ribs at a, lower'level than lthe outer rim, and the spades 1 may be concaveor scoop shaped. The spades 1 may also in someV cases be formed with prongs to facilitate their entrance amongst gravel.

What clairn as my invention, and desire to secure by Letters Patent, is-

1. The framework 2, to the outer edges of which is hinged-directly a series of spades I, in combination with the within-described system of chains A and B, the whole being arranged and operating substantially as and for the purpose herein set forth.

2. The combination of the above with the hook 7, constructed and operating in combination with the chains attached te the frame and to the spades as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN MILRQY.

Witnesses:

EDMUND HUNT, Glasgow, AnoLF SJOBERG, Glasgow. 

